The invention relates to the control of the fuel supply for an internal combustion engine. More particularly, the invention relates to a method and an apparatus for engaging an existing fuel preparation system in an internal combustion engine so as to provide fuel mixture enrichment for an intended acceleration of the engine. In known fuel preparation systems, for example in fuel injection systems, there may be present an air flow rate meter disposed within the induction manifold of the engine which generates a, usually electrical, signal that is a measure of the position, i.e. the opening, of the throttle plate and hence a measure of the air flow rate into the engine. However, inasmuch as carburetors or other fuel preparation systems also measure the air flow rate directly or indirectly, the method and apparatus of the invention would, in principle, be suitable for use in association therewith. When the operator depresses the gas pedal rapidly, the air flow rate metering flap of the known fuel injection system tends to move quite far in the direction indicating a full-load, i.e. fully opened throttle, and then subsequently swings back again while being damped to a relatively small degree. During the return swing of the air flow rate meter, the system indicates a relatively low load condition which is incorrect and which is less than the actual load of the engine, i.e. less than the actual opening of the induction tube throttle and hence does not correspond to the air flow rate actually admitted to the engine. Any fuel control measures, for example fuel injection control pulses which are based on the indications of the air flap during its return swing, will thus be too small or too short and will result in providing to the motor an insufficient amount of fuel. This type of condition may cause a delay in the acceleration in spite of rapid gas pedal actuation and may, in fact, cause the engine to stall. It is also possible for explosions to occur in the induction manifold.
It should be noted that the first excursion of the baffle plate within the air flow rate meter subsequent to an accelerating motion of the gas pedal is generally desirable because it results in an excessive amount of fuel being delivered to the engine during a rapid acceleration. Unfortunately, this initial enrichment is effective for only a short time and thus can affect only those fuel injection pulses which occur prior to the return swing of the baffle plate.